Electronic devices are prevalent and in everyday use. Electronic devices utilize communication bus protocols to be able to communicate with and transmit/receive power to and from each other in a more uniform or standardized manner Universal bus communication protocols, such as Universal Serial Bus (“USB”), as well as proprietary bus communication protocols, such as the bus protocol for Apple's Lightning® bus connectors, exist and are well known.
USB is a well-known industry bus communication protocol for electronic devices. USB provides a well-defined standard protocol that allows electronic devices to communicate with each other. Various versions of the USB protocol exist, such as USB 1.x, USB 2.0, USB 3.0, USB 3.1. USB-C and USB-PD protocols add the ability to provide power delivery. Apple, Inc. has established its own proprietary bus communication protocol that is compatible and compliant with its Lightning bus connector that allows devices to communicate with and respectively provide/receive power to and from Apple devices.
It is well known that many portable hosts implementing bus communication protocol connectors (such as USB-C or Lightning connectors) provide a single port only that is useful for either communicating data or providing power or both under specific conditions. Hubs and docks provide multiple ports that resolve the single port limitation and have the ability to provide power to an electronic device and a portable host. However, both hubs and docks add a significant amount of complexity and cost to overcoming the single port limitation and power provision problem. Furthermore, hubs and ports (such as USB-C hubs and ports) with at least one downward facing port (DFP) require additional testing for certification (e.g., USB-C certification).
To avoid the complexity of hubs and docks and certification requirements, passthrough charging (or pass-through charging) has been adopted and used in electronic devices via some bus communication protocols. Passthrough charging allows an electronic device that is coupled to a power source and to a host to use the bus communication protocol to allow normal operations between the electronic device and the host, and also to allow charge to pass through the device to a host. The host receives the power/charge from the power source and the host, in turn, powers/charges the electronic device also via the bus communication protocol. Passthrough charging may not allow the power source to directly power/charge the electronic device but always requires that the host first receive the passthrough power/charge and then, secondly in turn, the host uses its power source to power/charge the electronic device. Passthrough charging allows devices to avoid having to have at least one DFP.
FIGS. 1A and 1B illustrate an example Apple Lightning compatible headphone device 10 (or a generic peripheral device) that provides the passthrough charging feature, as is known in the art. FIG. 1A depicts an external view of headphone device 10 while FIG. 1B is an illustration of a block diagram depicting headphone device 10 interfaced with a power charger (PW CHG) 11 and a host 14. Example hosts 14 include but are not limited to smart phones, tablets, and personal computers. Referring to FIGS. 1A and 1B, headphone device 10 may be coupled to host 14 via Lightning port 12B and Lightning host port 16. First contacts of Lightning ports 12B and 16 may be used to provide normal operations and communicate data via data block (DATA) 19 of host 14 and headphone data block (HP DATA) 15 of headphone device 10 between the headphone device 10 and host 14. When power charger 11 is coupled to headphone device 10 via Lightning port 12A, charge may be passed through headphone device 10 via passthrough line (PT) to host 14 from Lightning port 12A through Lighting port 12B to Lightning host port 16. Second contacts of Lightning ports 12B and 16 may be used to provide power between the host 14 and the headphone device 10. Host 14 may receive charge (e.g., from power charger 11) at its battery (BATT) 17. Host 14, in turn, may provide the charge to headphone device 10 by providing charge from its power (PWR) block 18 to headphone power block (HP PWR) 13. In this embodiment, power charger 11 may never directly power/charge headphone device 10, and power/charge for headphone device 10 may also have to be passed through headphone device 10 to host 14 and host 14, in turn, may have to power/charge the headphone device 10. An example of such headphone device 10 is Pioneer Rayz Plus® Lightning headphones/earbuds.
FIGS. 2A, 2B, and 2C illustrate an example adapter device 20, as known in the art, that may allow electronic device operations between it and a host as well as providing passthrough charging which allows charge to pass through the electronic device to the host and may allow powering/charging of the electronic device by the host. FIG. 2A depicts adapter device 20 having bus communication ports 22A, 22B, and 22C. Bus communication ports 22A, 22B, 22C, 12C, and 14A may be Lighting ports, USB-C ports, or any other type of bus communication ports. Ports 22A, 22B, 22C, 12C, and 16A are not limited to any type and can each be of a female type and/or a male type. Similar to host 14, example hosts 14A may include but are not limited to smart phones, tablets, and personal computers.
Referring now to FIG. 2B, headphone device 10A is shown coupled to adapter device 20 via ports 12C and 22B, and host 14A is shown coupled to adapter device 20 via ports 16A and 22C. First contacts of ports 16A, 22C, and 12C may be used to provide normal operations and communicate data via data block (DATA) 19A of host 14A and headphone device data block (HP DATA) 15A of headphone device 10A through adapter device 20. When power charger 11 is coupled to adapter device 20 via port 22A, charge may pass from power charger 11 through adapter device 20 to host 14A (e.g., passthrough charging) via passthrough line (PT) from 22A to port 22C to host port 16A. Second contacts of ports 22C and 16A may be used to provide power from the power charger 11 to the host 14A. Host 14A may receive the charge (e.g., from power charger 11) at its battery (BATT) 17A. Host 14A, in turn, may provide the charge to headphone device 10A through adapter device 20 by providing the power/charge from a power (PWR) block 18A of host 14A to a headphone power block (HP PWR) 13A via ports 16A, 22C, and 22A. In this embodiment, the power charger 11 may never directly power/charge headphone device 10A, and power/charge for the headphone device 10A may also have to be first passed through adapter device 20 from power charger 11 to host 14A and then host 14A, in turn, may have to power/charge headphone device 10A.
Referring now to FIG. 2C, headphone device 10A is shown instead coupled to adapter device 20 via ports 12C and 22A, and host 14A is shown coupled to adapter device 20 via ports 16A and 22C. First contacts of ports 16A, 22C, and 12C may be used to provide normal operations and communicate data via data block (DATA) 19A of host 14A and headphone device data block (HP DATA) 15A of headphone device 10A through the adapter device 20. When power charger 11 is coupled to adapter device 20 via port 22B, charge may be passed from power charger 11 through adapter device 20 to host 14A (e.g., passthrough charging) via passthrough line (PT) from port 22B through port 22C to host port 16A. Second contacts of ports 22C and 16A may be used to provide power from power charger 11 to host 14A. Host 14A may receive the charge (e.g., from power charger 11) at its battery (BATT) 17A. Host 14A, in turn, may provide the charge to headphone device 10A through adapter device 20 by providing the charge from power (PWR) block 18A of host 14A to headphone power block (HP PWR) 13A via ports 16A, 22C, and 22B. In this embodiment, power charger 11 may never directly power/charge headphone device 10A, and power/charge for headphone device 10A may also have to be first passed through adapter device 20 from power charger 11 to host 14A and then host 14A, in turn, may have to power/charge headphone device 10A.
An example of such adapter device 20 is Belkin International Inc.'s Lightning Audio+Charge RockStar™ adapter. Also, as indicated before, another example of adapter device 20 is a USB-C adapter device that may provide a passive analog audio adapter with passthrough charging capability. Such a USB-C adapter may have the three ports 22A, 22B, and 22C in which ports 22A and 22B may be the respective headphone (e.g., data) port and power port while port 22C may be the host port. However, such a USB-C adapter device has limits to minimum default power (e.g., 500 milliamps), and thus charge times of the host may be long. Also, such adapter may be a fixed function analog interface and thus may not support any of the other functions defined by the USB standard (e.g., mass storage device, keyboard, mouse, etc.).
Peripheral devices are well known in the art. A peripheral device is not a hub or a dock or an adapter device, such as adapter device 20. A peripheral device may be an ancillary device that is used to communicate information to a host and vice versa. One key disadvantage of existing approaches to passthrough charging is that power provided through a power charger may have to be managed and split between the host and the peripheral device. FIG. 3 illustrates an example high-level block diagram depicting this disadvantage of existing approaches to passthrough charging. Passthrough charging using existing approaches may be done serially, such that power from a power charger is provided serially. Because power is provided serially, the amount of power being provided to the host and peripheral device may need to be split accordingly. Also, the amount of power being provided by the power charger 11 may be limited to the maximum power that the host 14 is able to receive. In the example of FIG. 3, the block diagram depicts that power charger 11 may be capable of providing 12 watts. The 12 watts provided by power charger 11 may be passed through the peripheral device 10 via passthrough line (PT) and may first be received by host 14. Because host 14 needs to in turn provide peripheral device 10 with 3 Watts (3 W), host 14 is powered with only the remaining 9 Watts (9 W=12 W−3 W). Another key disadvantage is that if the host 14 is not coupled to peripheral device 10, using existing approaches, peripheral device 10 cannot be charged at all because power charger 11 cannot directly charge peripheral device 10. Such a direct charging feature is important and beneficial if peripheral device 10 is to be a standalone or wireless device, such as a wireless headphone/headset/earbuds.